The expected rates of returns on the French films Renault and publics, the market portfolio (CAC 40) and the risk-free assets are given below, along with the standard deviations of these returns

Asset	Expected return (%)	Standard deviation (%)
Publicis	17	40
Renault	10	20
CAC 40	14	17
Risk-free asset	3	0

a) Assuming that the returns are explained by CAPM, specify the betas for Publicis and Renault, and the risk of the portfolio of these two companies with an expected return the same as CAC 40

b) Specify the composition of a portfolio consisting of the CAC 40 and a risk-free asset that will produce an expected return of 10%. Contrast the risk of this portfolio with the risk of Renault.